In accordance with deadlines set in 2018 legislation, the California State Water Resources Control Board has adopted a definition for “microplastics” that will be used in testing of drinking water for microplastics. The Board was required, on or before July 1, 2020, to adopt a definition of microplastics in drinking water and, on or before July 1, 2021, will be required to adopt requirements for testing and reporting on microplastics in drinking water, among other things. While this development is currently focused on the testing of drinking water in California, the Board and others expect that it will form the basis of future efforts to quantify and address microplastics in the environment.